


Percy Jackson and the Mermaid Tail

by katiecunning404



Category: Percy Jackson and the Olympians - Rick Riordan
Genre: Comfort, F/M, Fluff, Humor, Little Mermaid Elements, Love, Sacrifice, Sass, mermaid, mermaid!percyau, merman, notcannon, persassy
Language: English
Status: Completed
Published: 2020-05-05
Updated: 2020-05-05
Packaged: 2021-03-02 20:27:31
Rating: General Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 4,913
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24022843
Author URL: https://archiveofourown.org/users/katiecunning404/pseuds/katiecunning404
Summary: Percy Jackson is a sassy merman. What more is there to say?
Relationships: Annabeth Chase/Percy Jackson
Comments: 2
Kudos: 77





	Percy Jackson and the Mermaid Tail

**Author's Note:**

> Disclaimer: This takes place in the timeline of the Last Olympian, and Percy was never the son of Poseidon

Look, I didn’t want to be a mermaid.

Being a mermaid means constantly looking over your shoulder for predators. It’s scary and dangerous - and can get you killed. Painfully.

I didn’t ask for this. It wasn’t my fault my mom fell in love with a rugged, fisherman-type guy, and it wasn’t my fault that fisherman-type guy was actually Triton, the bearded guy with the trident in Little Mermaid. 

I didn’t choose to be born with gills and webbed hands and a blue tail (even though my tail is pretty sick). My mom took one look at me and knew I wasn’t normal. At least not in mortal terms. 

I don’t remember much about my mom after she was forced to hand me over to the other mermaids, and Triton doesn’t talk about her. He doesn’t talk about any of his mortal conquests, so it’s no surprise that he didn’t make an exception for me. 

All I have left of her is the name she gave me and a picture of her in the drawer of my bedside table. I gave one of the demigods at Camp Half-Blood a hippocampi ride in order to get it. Travis and Conner might be mostly mortal, but they’d do anything for a thrill. That was the first and last time I went to Camp Half-Blood. The kids there don’t like mermaids.

The only thing my mom and I have in common is our black hair and olive skin. Her eyes are pale blue, but mine are a blue-green - the color of the sea. Triton’s eyes.

He’s a sucky father, too. More dictator than dad. It doesn’t help that I’m the offspring of a mortal, not another mermaid. My three half-sisters enjoy rubbing that fact in my face - as if I could forget it. They get to sit in thrones alongside Triton in the royal court. What do I get?

A huge stinking pile of nothing.

I stared at them now, my sisters sitting primly in their coral thrones. Since I’m not part of the royal family - not _technically_ \- I stayed in the shadows of one of the alcoves of the throne room, peering out from behind a slab of marble. I might be half-mortal trash, but at least I know how to sneak around the palace. 

“Kronos and his forces are growing with every passing day,” said Triton from his throne, the trident in his hand glinting in the shimmering waters. “Poseidon is asking us to offer our forces for aid.”

The nymph advisors surrounding Triton nodded thoughtfully, but excitement buzzed beneath my skin. Kronos was waging war against the gods. And Atlantis had the opportunity to fight.

With years of nothing to do but train with the other mermen, learning from some of the most experienced warriors beneath the sea, I was eager for a fight. I was sick of being trapped beneath the waves, swimming and sparring with no purpose. I wanted to do something _real_ \- something that mattered.

I could fight. Only if Triton accepted Poseidon’s offer.

My tail lashed anxiously beneath me as one of the advisors said, “Are our troops prepared for such a battle?”

 _Yes,_ I wanted to say. _We’re ready, we’ve been ready._

But one of the other advisors spoke. “I don’t know that this is wise, my lord. Poseidon offers us nothing, ignores our requests, until this moment when he needs us in order to succeed.”

I held my breath, waiting for Triton’s response. 

“I agree,” said the sea king. 

My stomach dropped.

The advisors murmured their approval, and my father continued. “Send word throughout the kingdom. I want Atlantis on lockdown until this all blows over.” 

I didn’t stick around long enough to hear the rest of his proclamation. As quickly as I could, I swam to my rooms on the other side of the palace. With shaking hands, I dug Riptide out of the sand of the ocean floor. I found the sword in the wreckage of a cruise ship, and it’s saved my life more times than one. There was no way I was going into a war without it.

I didn’t give myself any time to think about how I was leaving Atlantis, the home that had never felt like home, possibly for the last time. When Triton found out I disobeyed his orders, I was in for a world of hurt. The sea god didn’t take kindly to people who didn’t listen to him. The fact that I was his child made no difference.

I swam as far and as fast as I could, traveling east to Camp Half-Blood. If they needed all the help they could get, I figured they wouldn’t care if I was a mermaid or a monster. The strand of shells around my neck brushed over my throat, reminding me of their power. They would get me to any body of water in the world, whether it was a lake or a river.

I wanted to fight. Even stupid Triton and his stupid decisions wouldn’t stop that.

Camp Half-Blood was deserted.

I pulled myself onto the sandy shores of the lake, gritting my teeth against the discomfort of being out of the water. After living underwater for 16 years, it’s weird to have air hit your skin. It’s like a current, but harsher. More painful.

And the light is so bright. Beneath the waves, sunlight gets filtered through layers and layers of tons of water - literal, two thousand pound _tons of water._ Which means I don’t get sunburned, but it’s hard to adjust to the world above. It took me a few moments to even see straight, and when I did, the sight shocked me.

There was no one on the dock, no one in the training yard, no one in the cul-de-sac of cabins. It was so quiet. No sound or glimpse of life anywhere. 

“It’s me, your friendly neighborhood merman!” I called, a hand cupped to my mouth. Just because I live in Atlantis doesn’t mean I’m uneducated.

The click of horse’s hooves made me glance to the side. An elderly centaur stared down at me, his bow drawn and leveled at my chest. I raised my hands as he said, “Who are you?”

“No need for weapons,” I said. Riptide lay in the sand a few feet away, but I didn’t try to grab it. “I’m Percy. I heard you guys might want some help with Kronos or whatever.”

That seemed to satisfy the centaur, and he lowered his bow. I could see his worry in the wrinkles of his brow. “Kronos is in New York City.”

I couldn’t stop the excited grin that curved my mouth. “Where exactly?” I asked.

“Why do you want to know? Last I hear, the merpeople refused to come to Poseidon’s aid,” the centaur said warily.

“Yeah, well, good thing I don’t answer to Triton. That arrogant jerk can go screw himself for all I care.” I could’ve used stronger language, but judging by the centaur’s stern expression, I didn’t think he’d approve.

A look of recognition passes over his features. “You’re Sally’s son, aren’t you?”

I couldn’t stop the sharp edge to my voice as I said, “How do you know her?”

“She’s been looking for you.” He smiled at me, and I couldn’t help but glare back. I hated the fact that he knew more about my own mother than I did. “She came to the camp to see if we’d heard from you.”

“What’d you tell her?”

He shrugged. “That apart from your visit to the Stoll brothers, none of us had heard from you.”

I didn’t say anything back. The reason I had stopped coming to the camp was because they were all normal. It hurt to know that they were children of gods, too, but they got to walk on two legs. They could pass as mortals, whereas I didn’t belong. Not to the sea, not to the land. I was something in between.

“If you truly want to fight,” said the centaur, his tone kind and grandfatherly, “go to the city.”

I nodded, slowly wriggling back into the water. “Who’s their leader?”

The centaur smiled, then. “A child of Athena. Annabeth.”

 _Annabeth._ I commited the name to memory as I grabbed Riptide and slid back into the water. “Thanks,” I said and slipped beneath the waves.

New York City was chaos.

Even from below the surface of the East River, I heard screaming and shouting, calls to arms and shrieks of pain. I did my best to stay hidden, but the deeper I dove, the more disgusting the water was. It was filled with dirt and candy wrappers and slime. Bleh.

Riptide still in hand, I moved along the barriers of the river and towards the bridge. A horde of monsters stood on one side, and a scraggly group of weary-looking demigods stood on the other. I kept to the water, watching as they charged at one another, weapons raised.

Then I realized how stupid I’d been. I couldn’t fight on land, and those monsters certainly wouldn’t jump into the river.

I had to bring the water to them.

That familiar power roared through my blood, a steady dreambeat in my ears. Triton might despise me for being half mortal, but at least he’d given me the power of the seas. I’d honed that power into a weapon that rivaled even the greatest of sea gods. I taught myself the language of the ocean, and now was my chance to speak it.

There was a tugging in my gut as a tidal wave - _my_ tidal wave - rose on the other side of the bridge. Out of the corner of my vision, I knew the demigods had seen me, that they were staring, but I was too focused on my task to care.

The monsters wailed at the sight of the wave, but they didn’t get out of the way in time as I brought the water down, launching them off the bridge.

Towards me.

I grinned at the sight of them - basilisks and telekhines and harpies, falling into the river. Riptide raised, I dove beneath the waters, my powerful tail propelling me forward.

They didn’t have time to scream before I was upon them, slashing and ducking and dodging their blows. I was faster than them, so every time one even tried to fight back, Riptide cut through them before they had a chance.

As much as I’d hated it, I was thankful for my tail, for the webbing between my hands. I had spent so much time underwater that I didn’t have to think before I was cutting them down. Their ichor was a song in my blood, the golden dust that meant the end of their life exploding around me. I was a killer beneath the surface, force to be reckoned with.

It wasn’t long before I’d destroyed the horde of monsters and shot to the surface, eager for more. I clung to the stone of the riverside, as close to the bridge as I dared without being directly under it. Gold dust stained my torso, my tail as I squinted against the sun, spying two figures standing on the bridge. I shouted, “Is that all you got?”

One of the figures, a demigod with blonde hair, whipped her head towards me. Spatters of blood ran down one side of her face, her armor ripped and torn in places, but she was beautiful. Her stormy gray eyes narrowing on me as if to say _Shut up you idiot!_

I realized how stupid I must have looked. A lone teenage mermaid in the muddied water of the East River, waving a sword.

A deep, dark chuckle sounded above the lapping of the waves. I looked away from the demigod to the other figure. It was a boy standing in place of the monsters, a wicked scar curving from the edge of his eyebrow to the line of his jaw. Once I saw his eyes, I knew that he wasn’t a boy. It was Kronos.

Cold fear curdled my blood, and evey one of my instincts screamed at me to run. But I saw the blonde-haired girl step forward onto the bridge, knife brandished. The scarred boy - Kronos - advanced towards her.

It was just the two of them. One on one. The demigods standing on the other side of the bridge called out to the girl, too busy fighting off monsters of their own to come to her aid. “Annabeth, stop! Come back!” one screamed, her voice raw and hoarse from battle cries. Annabeth didn’t flinch. She kept walking.

I glanced between them with wide eyes. The smirking Titan and the girl who raised her knife. “Get out of him,” she ground out.

“I’m afraid that can’t happen,” said Kronos. His voice grated over my bones, and I fought not to shudder.

“Fine,” Annabeth hissed. “Then I guess I’ll just kill you.”

What could I do? What could I do? There were no more monsters to fight, only Kronos. And he was a Titan, whereas I was something else entirely. Mortal. Not supposed to exist. Unwanted. 

Whatever I was, I had to move quickly, before Kronos killed her.

The roaring in my gut grew, but I pushed it down. She was the leader of the demigods, I reminded myself. She could handle herself.

With bated breath I watched them stare one another down. Watched as Kronos hefted his wicked-looking sword and swung it down onto Annabeth.

She dodged the blow and stabbed toward him, but Kronos was fast. Much too fast, I realized. It was only five seconds into the fight and some innate part of me already knew. Annabeth would die.

Unless I did something.

I left the security of the riverbank and swam to the center of the river, where I could better see the fight. The daughter of Athena blocked one of Kronos’s blows with the hilt of her knife, but I could see her shoulders sag. She was getting tired, and it was understandable. Kronos hadn’t broken a sweat, still swinging his sword at full force.

Power churned through my veins, but I forced it down. I had to wait for the perfect moment, when I could take Kronos into the water without washing Annabeth off the bridge, too. My hands shook, and I tightened my grip on Riptide.

Kronos brought his blade down on Annabeth, and, too slow to move out of the way, she caught it on the blade of her knife. Her attention was so focused on the cross of their blades, on holding his strike at bay, that she didn’t see his foot come up. He drove his foot into her stomach, and Annabeth hit the ground. 

I heard her skull crack onto the pavement, and my power exploded.

I had enough sense not to send another tidal wave over the bridge - that would drag both Kronos _and_ Annabeth into the river. Instead, my power picked me up in a spiral of water and ichor and threw me onto the bridge.

Kronos had his sword raised for the killing blow, that sick smirk still carved into his face. I landed just short of crushing Annabeth’s legs beneath my tail and lifted Riptide in front of me. His blade cracked into mine. 

Shock took hold of his features for a moment, and I took advantage of the fact to glance at Annabeth. Her eyes were closed, her breathing shallow, but she was alive. Thank the gods.

Kronos’s surprise was immediately replaced by anger. He tried to stab into the fins at the end of my tail, but I jerked them away before he could. The hot pavement bit into my scales. “Pretty sure that’s considered animal cruelty,” I said.

His snarl made it clear the Titan didn’t care about animal cruelty. Must be more evil than I thought.

I summoned a small wave to carry Annabeth to the edge of the bridge, another to momentarily blind Kronos. He bellowed his outrage, swinging his sword blindly in front of him.

A whirlpool of water picked me up from the asphalt, and I instantly felt refreshed. But my relief only lasted so long, because time slowed.

And it wasn’t adreneline or one of those things were something seems really long, like a lecture about quantam chemistry or a conversation with someone that you don’t like. Time itself slowed, and I was suspended above the bridge, helpless.

Kronos gave me a sly grin, spitting out water as he stared at me. “I thought the merpeople stayed home in their magic city,” he said. “Looks like you’re alone.”

I swallowed slowly, betraying my fear. I was alone. Hadn’t I always been alone? The only mortal son of Triton? The thing that wasn’t human but also wasn’t something else? Yes, I decided. I had been alone. 

Now, with Kronos advancing on me, his massive sword gleaming at his side, I would die alone.

At least, that’s what I thought before a rotten tomato crashed into the Titan’s face. 

His focus on stopping time faltered, and I could move freely again.

“Hey! It’s Percy!” I grinned at the sound of Connor’s voice behind me. I turned to see the Stoll brothers carrying a basket of rotten fruit and vegetables between them. Chucking them at Kronos and cackling with the mischief of Hermes himself. Every piece of food hit its mark. I laughed.

Eager to help, I blasted the Titan with as much water as I could pull out of the river while still keeping myself aloft over the pavement. Even as I felt my power near its limit, I kept going. 

I was so focused on hitting him with the river and smiling alongside the Stoll brothers that I didn’t see Kronos’s hand shoot out and close around my wrist. 

With the full strength of a Titan, he tossed me off the bridge, as hard and as fast as he could. Riptide flies out of my grip, clattering onto the asphalt. 

Before I could fall into the river, though, I dug my fingers into the edge of the bridge. The webs of my hand burned from the stone, but I gripped it with all my might. I reached for my power, but my heart sank when I realized it was gone. I’d used it all on Kronos, and he still hadn’t fallen off the bridge.

If I fell off, I’d never get back on.

It took most of my strength to push myself to my elbows, and I almost lost my grip when I saw where Kronos was. Stalking towards Annabeth, who still lay unconscious on the street.

I tried to stay silent as I pushed against the asphalt, fighting to get my tail over the edge. There was nothing to push off of, and even if there was, my tail wasn’t built like human legs. On land, it was a useless piece of muscle.

(Author’s note: Useless piece of _mussel._ Haha. I’m hilarious.)

Tails suck.

Somehow, after several tries, I manage to swing my tail onto the pavement. Bleeding cuts were scattered between my scales, stinging in the air. Kronos was stalking towards Annabeth as I pushed onto my hands.

“Kroney!” I yelled. When he kept walking, I said, “You’re going after an unconscious girl? Too scared to fight something that can actually fight back?”

At that, he paused. I mentally congratulated myself as he turned to face me. _Good job Percy, you caught the attention of a Titan about to kill you! Now what?_

“This is not your fight, son of Triton.” I forced myself to smile despite the insulting tone of his voice. 

“Atlantis was getting boring,” I said. “Besides, they made you sound so stupid I had to see for myself.”

He bristled, his sword arm tensing. “Who?”

“Who what?” I asked innocently.

I fought not to flinch as Kronos leveled his blade at my throat, pit black eyes staring into my soul. “Who spoke of me in such a way?”

“Oh, that was me. I have a daily conversation with myself in the mirror - you know, to check up on myself. See how I’m doing. You happened to come up in conversation. An honor, really. Those conversations are of the utmost importance to my mental health. So really, I should be saying thank you.” I was talking nonsense, but I needed to keep him away from Annabeth as long as I could. 

Kronos tilted his head at me, as if he couldn’t believe how stupid I was. I couldn’t believe it either. 

My gills were burning in the sun, and I felt the blue scales in my tail ripping and tearing over the pavement. I was drying out.

The Titan stabbed down, and I yelped as his blade sliced through my arm. I was powerless to stop him, a fish out of water with no reinforcements. My training in Atlantis meant nothing on land, and Riptide was too far away from my grasp. All I had to do was hold him off until my powers came back.

But then I had an idea. A ridiculous, will-probably-get-me-killed idea.

I inhaled as deeply as I could, making a show of closing my eyes. As I opened them wide, I straightened my posture as much as possible, locking my elbows beneath me. “Do not touch the creatures under my domain,” I said in a deep, rough voice.

Kronos’s triumphant grin faltered. “Poseidon?” he sneered.

I kept my features serene, fighting to hide the pained whimpers clawing up my throat. My entire body felt like it was on fire. “Do not harm the boy,” I repeated, summoning as much crisp authority as I could. 

“I do not take orders from you,” the Titan spat. “Your creature is at my mercy.”

A swell of power buzzed through my veins, and I grinned. “Not anymore,” I said as a wave of my own creation crashed over me. I flung my power out to Annabeth and grabbed her as the waters carried us both off the bridge and into the disgusting river.

The moment I entered the waters of the East River, the pain of the cuts and burns over my body subsided. Kronos’s stab wound in my upper arm stayed deep and hurting, and I gritted my teeth together.

Annabeth was a limp weight beside me, and I used the dregs of my power to form a bubble around her. The last thing I needed was a drowning demigod.

Explosions shook the world above me, and it was an effort not to throw myself back into the fight. One thing at a time. First I had to get Annabeth to safety - then I could deal with the Titan.

It took a few minutes to find shore far enough away from danger. The last of my power was spent placing Annabeth on the pebbled shore - gently, so I didn’t make any more damage. The cries of demigods and monsters alike echoed far in the distance.

I heaved myself out of the water, my breath coming in ragged pants. The stones below dug into my scales, and I considered going back in the water. But she might have been more injured than I thought, and I needed to make sure she woke up. 

Curse my morals. 

Inch by miserable, agonizing inch, I dragged myself forward towards the daughter of Athena. My webbing caught between the rocks, but I pushed through the pain until my breath was coming in short bursts. I flopped down beside her, my turquoise tail gleaming in the sun.

Every breath hurt. I was used to breathing through my gills, so every gulp of air I took through my nose and mouth felt like fire burning my throat. I clasped my hand on Annabeth's shoulder and shook her. All I got was the rattle of Greek armor.

“Come on,” I groaned. “Wake up.” I shook her again, and her head lolled to the side.

No sign of the warrior I’d seen on the bridge. None of the fierceness I’d seen in her eyes. Just a tired, broken demigod.

Weren’t they all.

I put two fingers on her neck, feeling for a pulse. I’d never felt for a pulse, but somehow I found it. What was a pulse supposed to feel like? I didn’t know, but it was there.

“That was pretty smart, trying to take on a Titan by yourself.” I pulled myself closer to her, looking for some sign that she’d heard me. “Not very wise.”

When she didn’t respond, I clicked my tongue. “Come on, wise girl. No comeback?” I sighed. “You don’t want me to do this. I’ve only seen it in movies.”

She just drooled. I sighed.

I put my hands, one on top of the other, over her chest. Where was the human heart? The left of the right side? I settled for the middle. Press down, pause, press down again.

There was some song you were supposed to go to, but the only song I could think of was Taylor Swift, the songs mortals blasted over the speaker systems of their cruise ships. So, like an idiot, I started to sing under my breath. “Cause the players gonna play, play, play, play, play and the fakers gonna fake, fake, fake, fake, fake, baby I’m just gonna shake, shake, shake, shake, shake-”

Annabeth slapped me across the face.

My elbows buckled beneath me, and I couldn’t move myself away from her without the use of my arms. My face landed on her stomach. “Ow,” I said.

“Who the heck are you?” she demanded, shoving my face off of her. I scrambled to find purchase in the pebbles beneath me so I could push myself up.

I looked up and found her face inches from mine, all the intensity of her gray eyes directed on me. “You drool when you’re unconscious,” was all I could say.

She scowled, but seemed to immediately regret it and put her hand to her head. “What happened?” she muttered. 

“Would you believe me if I said you fell into the East River and would have drowned if not for a handsome merman who swept you up in his arms and saved your life?” I asked.

Rolling her eyes, Annabeth shook her head. “I didn’t know mermen had seaweed for brains.”

“Well, that’s just me.” I heard shouting, and my jaw tightened at the sound of mortal voices. “And that’s my cue to leave.”

She glanced over her shoulder, then looked back at me. Really looked at me, this time. I winced when she saw my tail, the gills at my throat, my webbed hands.

“Oh my gods, what happened to your arm?” she said. Concern flickered in her gaze.

Blood colored the edge of my vision, and I cringed. Beneath the surface, blood didn’t flow as freely as on land. “Kronos used me as a pin cushion.”

Annabeth crawled to my side, and I swallowed my discomfort as she took my arm in her hands and peered at the wound. “I might have some gauze in my belt,” she murmured. I watched as she pulled a roll of white bandage out of her belt and ripped off a generous strand with her teeth. 

Her blonde hair tickled my face as she wrapped the wound, jaw set in focus. “There,” she said, sitting back to admire her work. “Watch it for a few days and make sure it doesn’t get infected. Though underwater…” She met my gaze, and I could see the thoughts running through her mind.

I expected her to ask about Atlantis, about how I breathed or how it was to be under King Triton’s rule, but instead she asked, “Why’d you come out of the water?”

I shrugged, the sun beating down on my back. “Had to make sure you were alright, wise girl,” I said.

Annabeth looked skeptical, but she nodded all the same. Slowly, she got to her feet, and I said, “Are you sure you’re okay?”

“Yep.” She walked behind me, and I swiveled my head around to keep her in my sights. 

She crouched before my tail and I blurted, “What are you doing?”

Annabeth gave me an incredulous look. “Helping you back into the water. I know it’s painful for you to be on land for so long.”

I blinked. Mermen weren’t special creatures. Very few demigods even gave my kind a second thought. “Thank you,” I said quietly, not sure what else to say.

“I’ll grab your tail, and you’ll just have to walk yourself back with your hands,” she said. I followed her instructions and fought my panicked yelp as she pulled my tail off the pebbles.

Slightly unsettled, I pushed with my hands as she walked back towards the water, setting my tail down carefully. She cleared her throat, and I frowned. Why was she uncomfortable?

“What’s your name?” she asked before I slipped beneath the water.

Swishing my tail to keep me afloat, I grinned at her. “Percy. But you’re welcome to call me ‘that stupid merman with seaweed for a brain’.”

“I’ll have to shorten it to ‘seaweed brain’,” she said drily.

I raised my hands in mock surrender. “As long as we’re in agreement. See you later, wise girl.”

Before she could respond, I dove into the water, the trail of bubbles behind me the only sign I was ever there.

  
  


**Author's Note:**

> I don't know how I feel about this but here we are.


End file.
